Pneumonia Organism May Play Role in MS Development

Toronto (April 23, 1999) — An agent that causes respiratory tract infections such as community-acquired pneumonia, called chlamydia pneumonia, may be a factor in the development of multiple sclerosis (MS) in some patients, according to a study released during the American Academy of Neurology 51st Annual Meeting April 17-24 in Toronto.

These results suggest that infection of the central nervous system with chlamydia pneumonia is an early event in MS, and may directly or indirectly be responsible for the development of the disease,” said study author and neurologist Subramaniam Sriram, MD, of Vanderbilt Medical Center, in Nashville, TN. “What is not clear is whether C. pneumonia is the cause of MS, a fortuitous bystander, or whether it in some way triggers an autoimmune response which causes the disease.”

The cause of MS is not known. In MS, the insulating material of the nerves, myelin, is destroyed. This leads to problems in vision, balance, gait, and other neurologic functions. Current theories suggest that a poorly regulated immune response against common infectious agents may be responsible for the disease.

Chlamydial species are well-known pathogens involved in a number of human diseases. Chlamydia pneumonia was discovered about 10 years ago and is now thought to be responsible for many cases of community- acquired pneumonia. The association between C. pneumonia and MS has not been previously noted.

In a study of 17 patients with newly diagnosed relapsing remitting MS and 13 patients without the disease, researchers found evidence of the chlamydia pneumonia organism in the spinal fluid of all 17 MS patients. In 47 percent of newly diagnosed MS patients, the organism was directly cultured from cerebrospinal fluid. Using sophisticated genetic tests, researchers found the DNA of chlamydia pneumonia in the cerebrospinal fluid of all the MS patients. In contrast, the organism was not found in the cultures of any of the 13 control patients, and only two had evidence of C. pneumonia DNA.

“There is a possibility that these two patients may develop MS in the future since their symptoms were suggestive of an initial attack,” Sriram said.

Also, a majority of the MS patients had an antibody response to chlamydial antigens in the cerebrospinal fluid, indicating evidence of a chronic immune activation to chlamydia pneumonia.

In earlier studies, the researchers had established that a large number of patients with chronic progressive MS had evidence of C. pneumonia infection in the cerebrospinal fluid. However, it was unclear whether the infection was a secondary event following long-standing inflammatory injury or was directly involved in the immune process, Sriram said.

“It’s clear from this study that the association between MS and the presence of C. pneumonia infection is extremely high–much higher than any other organism people have looked at in the past,” he said.

“Since a number of currently available antibodies prevent the replication of C. pneumonia, a therapeutic trial is likely to answer the question of cause and effect between C. pneumonia and multiple sclerosis,” Sriram said.

This study was supported by the National MS Society.

Improving care for patients with neurological disorders through education and research is the goal of the American Academy of Neurology, an association of more than 15,000 neurologists and neuroscience professionals.